1. Field of the Invention
The present invention relates generally to electrical switches. More particularly, the present invention relates to an electrical switch assembly for a key-in warning system of a motor vehicle, the switch assembly having circuits that are closed by the movement of electrical contact pairs within the assembly in a direction that is transverse or oblique relative to the direction of the force applied to an actuating body inserted into the assembly.
2. Description of the Prior Art
A simple electrical-mechanical switch typically includes an insulated actuator connected to one or more electrical conducting contacts contained within a housing. The actuator may be a physical body that receives a force applied thereto by a switch operator. When the actuator body is displaced by the application of a force, the contact on the actuator moves relative to the housing and makes physical contact with a second contact within the housing, thereby closing an electrical circuit. Typically, the relative movement of the contact pairs is such that they abut against each other in the closed position.
This is the case, for example, in a simple button switch that has a switch head attached to a shaft that is itself attached to one-half of a contact pair. When a person presses a finger against the button switch head, it causes the button to displace the shaft, which causes the contact attached to the end of the shaft to likewise move until it abuts against the other half of the contact pair, thereby closing an electrical circuit.
For purposes of this discussion, a “circuit” is a combination of a number of electrical devices and conductors that, when interconnected to form a conducting path, fulfill some desired electrical or electronic function. An electrical switch can form a part of that conducting path. One problem with switches utilizing contacts that abut each other in the manner described above is that debris can build up on the adjacent surfaces of the contact pairs over time. The build-up of debris can reduce the reliability of the switch in terms of its ability to close an electrical circuit. Debris can find its way onto contacts through openings on the switch housing, such as openings around actuating members that extend from outside to inside the switch housing.
Another problem associated with contacts that abut against each other is that the contact pairs can become deformed if the actuator is displaced too much.
Still another problem with contact pairs that abut against each other is that a pair of contacts in such an arrangement is typically able to close only one circuit at a time.
One solution to those problems is to use a sliding switch assembly. U.S. Pat. No. 5,860,515 to Tomotoshi discloses one such sliding contact. In Tomotoshi, an actuator 10, as shown in FIG. 3, causes a switch-operating member 4 to slide along a rail 19 that is part of a frame body 7. Inside the frame body 7 is a fixed circuit board 1, as shown in FIG. 1. The operating member 4 is attached to a sliding board 3 that includes five contacts 21 that are in slidable contact with fixed contacts 11 on the circuit board 1. In operation, as the operating member 4 moves along the rail 19, the contacts 21 sweep across the surface of the circuit board 1. Depending on the relative position of the contacts 21 and fixed contacts 11, several different circuits may be closed at one time. Although not described as an advantage of the disclosed invention, the sweeping action of the contacts 21 on the fixed contacts 11 can clean the portions of the contacts that physically touch each other and also prevent the contacts from being deformed.
U.S. Pat. No. 6,559,400 to Hayashi discloses a sliding switch assembly for use in a motor vehicle electrical system. In Hayashi, a slidable contact 15, as shown in FIGS. 2A-2C, moves parallel to base member 11 when a force component is applied in the longitudinal direction parallel to the slidable contact 15. Plate spring contacts 15E slide with the slidable contact 15 and contact the contact portions 12A and 14A, as best seen in FIG. 2C. The Hayashi sliding switch assembly is designed to close one of two different circuits, like those associated with a pair of motorized exterior rearview mirrors on a motor vehicle.
Both of the inventions disclosed in Tomotoshi and Hayashi involved sliding switches that are actuated primarily by an operator applying direct force to the actuator bodies of the respective switch assemblies using, most likely, a finger. However, other electrical switch assemblies for motor vehicles are actuated by a body or member that is interconnected to one or more different bodies or members, only one of which is actually touched by the vehicle operator. One example of this type of switch assembly is a key-in warning system switch. In the case of a key-in warning system switch, a plunger is used to cause an actuator to move electric contacts to close an electrical circuit. The plunger is in direct or indirect contact with the vehicle ignition key when the key is inserted into the ignition cylinder. Thus, the key, which the operator manipulates, is interconnected to the key-in warning switch actuator. The insertion or turning force applied to the key by the vehicle operator is transferred through interconnected members to the plunger that causes an actuator to engage the electrical contacts.
Force transfer actuators having multiple interconnected members are not new. U.S. Pat. No. 5,187,336 to Lang et al., for example, discloses a switch assembly with a transfer actuator. The switch assembly in Lang et al. has an external actuator arm 18, as shown in FIG. 1 of the patent, that causes internal component members to move relative to the switch housing when a force is applied to the actuator arm 18. Those component members then close an electrical circuit. The direction of the main component of the force applied to the actuator arm 18 is disclosed as being approximately orthogonal to the direction of the force that causes the member inside the housing to move.
In the case of a key-in warning switch assembly, the plunger is not directly connected to the switch housing but travels in a slot in the housing and causes electrical contacts to abut against each other and close an electrical circuit. One of the problems with this type of design, as noted above, is that the plunger can move too far and damage the contacts, plus there is no sweeping action to clear the contacts of debris that may build up.